What is The Three Laws of Robotics?

The basic precepts programmed into all posetronic robots, the Three Laws of Robotics specify that: 1) a robot may not injure a human or allow one to come to harm; 2) a robot must obey human orders unless such orders would conflict with the First Law; and 3) a robot must protect its own existence, unless this conflicts with the First or Second Law. R. Daneel Olivaw postulates a "Zeroeth Law" that : a robot may not harm humanity at large, or allow it to come to harm. After serving for decades in the Imperial Court as Eto Demerzel, Daneel reverts to his true nature and disappears to concentrate on the troublesome Zeroeth Law, which humans themselves make so difficult to obey. Over millennia Daneel has intervened in history only when absolutely necessary. He is the force behind Hari Seldon's science of "psychohistory."